To begin with, information will be harvested from existing databases, such as FishBase which already contains details of 29,900 species.

"One of the big tasks in the first six months will be to identify which groups we will focus on after that," Graham Higley of London's Natural History Museum, one of the partners in the project, told the BBC News website.

As the archive grows, it will become a "web of life" that will represent the relationships between different species on Earth.

During this gestation, teams of scientists will pore over it.

"They will be looking to identify species where the information is thin - and it is on an awful lot of species - to make it more comprehensive and usable," said Mr Higley.

The database has been in development since January 2006, although web pages dedicated to individual species have been produced ad hoc since the mid 1990s.

The scientists involved in the project said that the ability to catalogue millions of entries on the web had only just become possible.

"Advances in technology for searching, annotating, and visualising information now permit us - indeed mandate us - to build the Encyclopedia of Life," said Dr Edwards.

It could eventually fill with many more species than the original 1.8 million known today. Biologists estimate that there could be anywhere between five and 100 million species on the planet.

Animal tags

Other projects have previously attempted to index life on Earth.

For example, the Catalogue of Life keeps a database of more than one million species.

However, according to Mr Higley, it does not have the level of detail that the proposed Encyclopedia of Life will eventually contain.

"It's a list of names," he said. "What it is not is a description of those species."

Other databases have taken the identification process one step further.

In 2005, scientists launched the Consortium for the Barcode of Life, an ongoing attempt to identify all species through a unique genetic marker system.

These "tags" are composed of the order of DNA letters in a particular gene found in mitochondria, the "power units" in cells.

The project has so far collected more than 250,000 barcodes and has described more than 27,000 species.